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XmlSerializer.UnreferencedObject Event

Occurs during deserialization of a SOAP-encoded XML stream, when the XmlSerializer encounters a recognized type that is not used or is unreferenced.

Namespace: System.Xml.Serialization
Assembly: System.Xml (in system.xml.dll)

public event UnreferencedObjectEventHandler UnreferencedObject
/** @event */
public void add_UnreferencedObject (UnreferencedObjectEventHandler value)

/** @event */
public void remove_UnreferencedObject (UnreferencedObjectEventHandler value)

In JScript, you can handle the events defined by a class, but you cannot define your own.
Not applicable.

The UnreferencedObject event only occurs when the XmlSerializer is used to deserialize an XML document that contains a SOAP message that conforms to section 5 of the World Wide Web Consortium (www.w3.org) document, "Simple Object Access Protocol (SOAP) 1.1".

Documents that conform to section 5 are in a special format. At the very least, such a document includes the main body of the SOAP message. However, rather than having all types defined inline in the document, some type definitions can be encoded as references to top-level elements in the document. Thus, for every element found in the main body that is a reference, there must be a corresponding element that contains the type definition. To correlate the referencing element and the type definition, the type definition has an id attribute set to a unique string ID and the referencing element has an href attribute that references the same ID.

 <Group xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" id="id1" n1:GroupName=".NET" GroupNumber="ZDI=" CreationDate="2002-05-02" xmlns:n1="http:'www.cpandl.com">
     <PosInt xsi:type="xsd:nonNegativeInteger">10000</PosInt>
     <GroupVehicle href="#id2" />
   </Group>
   <Vehicle id="id2" n1:type="Vehicle" xmlns:n1="http://www.w3.org/2001/XMLSchema-instance">
     <licenseNumber xmlns:q1="http://www.w3.org/2001/XMLSchema" n1:type="q1:string">1234</licenseNumber>
   </Vehicle>

The UnreferencedObject event occur when there is a type definition found in the document, but no parameter in the main body references it. When the event occurs, you can retrieve the XML type of the unreferenced object by examining the UnreferencedObject property of the UnreferencedObjectEventArgs class. The XML ID of the object is returned by the UnreferencedId property.

The UnreferencedObject event should not be confused with the UnknownElement and UnknownNode events, which occur when there is no class member that corresponds to the XML node or element type.

The following example adds an UnreferencedObjectEventHandler to an XmlSerializer. The event is handled by the Serializer_UnreferencedObject method. To run the example, cut and paste the following XML into a file named "UnrefObj.xml".

 <wrapper>
   <Group xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" id="id1" n1:GroupName=".NET" xmlns:n1="http://www.cpandl.com">
    </Group>
 <Vehicle id="id2" n1:type="Vehicle" xmlns:n1="http://www.w3.org/2001/XMLSchema-instance">
     <licenseNumber xmlns:q1="http://www.w3.org/2001/XMLSchema" n1:type="q1:string">ABCD</licenseNumber>
   </Vehicle>
 <Vehicle id="id3" n1:type="Vehicle" xmlns:n1="http://www.w3.org/2001/XMLSchema-instance">
     <licenseNumber xmlns:q1="http://www.w3.org/2001/XMLSchema" n1:type="q1:string">1234</licenseNumber>
   </Vehicle>
 </wrapper>
using System;
using System.IO;
using System.Text;
using System.Xml;
using System.Xml.Serialization;
using System.Xml.Schema;

// You must use the SoapIncludeAttribute to inform the XmlSerializer
// that the Vehicle type should be recognized when deserializing.
[SoapInclude(typeof(Vehicle))]
public class Group
{
   public string GroupName;
   public Vehicle GroupVehicle;
}
 [SoapInclude(typeof(Vehicle))]
public class Vehicle
{
   public string licenseNumber;
}

public class Run
{
   public static void Main()
   {
      Run test = new Run();
      test.DeserializeObject("UnrefObj.xml");
   }
   
   public void DeserializeObject(string filename)
   {
      // Create an instance of the XmlSerializer class.
      XmlTypeMapping myMapping = 
      (new SoapReflectionImporter().ImportTypeMapping(
      typeof(Group)));
      XmlSerializer mySerializer =  
      new XmlSerializer(myMapping);
 
      mySerializer.UnreferencedObject += 
      new UnreferencedObjectEventHandler
      (Serializer_UnreferencedObject);

      // Reading the file requires an  XmlTextReader.
      XmlTextReader reader= 
      new XmlTextReader(filename);
      reader.ReadStartElement();

      // Deserialize and cast the object.
      Group myGroup; 
      myGroup = (Group) mySerializer.Deserialize(reader);
      reader.ReadEndElement();
      reader.Close();
   }

   private void Serializer_UnreferencedObject
   (object sender, UnreferencedObjectEventArgs e){
      Console.WriteLine("UnreferencedObject:");
      Console.WriteLine("ID: " + e.UnreferencedId);
      Console.WriteLine("UnreferencedObject: " + e.UnreferencedObject);
      Vehicle myVehicle = (Vehicle) e.UnreferencedObject;
      Console.WriteLine("License: " + myVehicle.licenseNumber);
   }
}

// The file named "UnrefObj.xml" should contain this XML:

// <wrapper>

//  <Group xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
//xmlns:xsd="http://www.w3.org/2001/XMLSchema" id="id1" 
//n1:GroupName=".NET" xmlns:n1="http://www.cpandl.com">
//   </Group>

//<Vehicle id="id2" n1:type="Vehicle" 
//xmlns:n1="http://www.w3.org/2001/XMLSchema-instance">
//   <licenseNumber xmlns:q1="http://www.w3.org/2001/XMLSchema" 
//n1:type="q1:string">ABCD</licenseNumber>
//   </Vehicle>

//<Vehicle id="id3" n1:type="Vehicle" 
//xmlns:n1="http://www.w3.org/2001/XMLSchema-instance">
//    <licenseNumber xmlns:q1="http://www.w3.org/2001/XMLSchema" 
//n1:type="q1:string">1234</licenseNumber>
//  </Vehicle>

//</wrapper>


import System.*;
import System.IO.*;
import System.Text.*;
import System.Xml.*;
import System.Xml.Serialization.*;
import System.Xml.Schema.*;
// You must use the SoapIncludeAttribute to inform the XmlSerializer
// that the Vehicle type should be recognized when deserializing.
/** @attribute SoapInclude(Vehicle.class)
 */
public class Group
{
    public String groupName;
    public Vehicle groupVehicle;
} //Group

/** @attribute SoapInclude(Vehicle.class)
 */
public class Vehicle
{
    public String licenseNumber;
} //Vehicle

public class Run
{
    public static void main(String[] args)
    {
        Run test = new Run();
        test.DeserializeObject("UnrefObj.xml");
    } //main

    public void DeserializeObject(String fileName)
    {
        // Create an instance of the XmlSerializer class.
        XmlTypeMapping myMapping = (new SoapReflectionImporter()).
            ImportTypeMapping(Group.class.ToType());

        XmlSerializer mySerializer = new XmlSerializer(myMapping);

        mySerializer.add_UnreferencedObject(new UnreferencedObjectEventHandler(
            Serializer_UnreferencedObject));
        // Reading the file requires an  XmlTextReader.
        XmlTextReader reader = new XmlTextReader(fileName);
        reader.ReadStartElement();
        // Deserialize and cast the object.
        Group myGroup;
        myGroup = (Group)mySerializer.Deserialize(reader);
        reader.ReadEndElement();
        reader.Close();
    } //DeserializeObject

    private void Serializer_UnreferencedObject(Object sender,
        UnreferencedObjectEventArgs e)
    {
        Console.WriteLine("UnreferencedObject:");
        Console.WriteLine("ID: " + e.get_UnreferencedId());
        Console.WriteLine("UnreferencedObject: " + e.get_UnreferencedObject());
        Vehicle myVehicle = (Vehicle)e.get_UnreferencedObject();
        Console.WriteLine("License: " + myVehicle.licenseNumber);
    } //Serializer_UnreferencedObject
} //Run

// The file named "UnrefObj.xml" should contain this XML:
// <wrapper>
//  <Group xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
//xmlns:xsd="http://www.w3.org/2001/XMLSchema" id="id1" 
//n1:groupName=".NET" xmlns:n1="http://www.cpandl.com">
//   </Group>
//<Vehicle id="id2" n1:type="Vehicle" 
//xmlns:n1="http://www.w3.org/2001/XMLSchema-instance">
//   <licenseNumber xmlns:q1="http://www.w3.org/2001/XMLSchema" 
//n1:type="q1:string">ABCD</licenseNumber>
//   </Vehicle>
//<Vehicle id="id3" n1:type="Vehicle" 
//xmlns:n1="http://www.w3.org/2001/XMLSchema-instance">
//    <licenseNumber xmlns:q1="http://www.w3.org/2001/XMLSchema" 
//n1:type="q1:string">1234</licenseNumber>
//  </Vehicle>
//</wrapper>

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0

XNA Framework

Supported in: 1.0

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